It accused the Dutch and Japanese-owned franchise of covering up serious safety breaches as managers were brought in to fill the safety-critical role after only a few days’ training.

The breaches include opening the doors on the wrong side of the train meaning passengers had to disembark straight onto the tracks.

RMT general secretary Mick Cash said he had written to the Chief Inspector of Railways again after news of another incident.

On a service from Norwich to Liverpool Street on Tuesday, an unskilled manager on the train left the door panel armed – having left the key engaged – while eating lunch in first class as the train was moving at high-speed.

Mr Cash said: “RMT has made numerous complaints to the rail safety regulator over potentially lethal safety breaches during this week’s strike action on Greater Anglia and they have completely ignored us.

“That is outrageous and points to deliberate collusion on a politically motivated basis. The regulator is supposed to be an independent body and is failing wholesale in its duty to the travelling public.

“Today we are again demanding action from the inspectorate and we expect them to drop this scandalous bias in favour of the private train operator.”